They are a way for people to carry around and display metadata about themselves. The basic bit of data is “I am allowed to be here”. Most conference passes add to that details such as who you are and who you work for. Some conference badges add in slots for customization such as press-clippings, your business card or whatever else you feel like tossing in there.

Everywhere you go, there’s the badge, broadcasting who you are and whether you are authorized. Anyone around can take a look and grab your data (such as it is). They are – as in all the lanyard augments – public, passive, and always-on.